This invention relates to an endless flat-type traction belt for a ski attachment for motorcycles, and in particular to a flat-type traction belt on which the traction means also serves as a sprocket engaging means for driving said belt.
The primary object of the present invention is to provide a traction belt which can be used on a ski attachment for motorcycles, similar to that described by Harris in U.S. Pat. No. 3,885,641. The ski attachment for which the belt of the present invention may be used, comprises skis that are adapted to be conveniently attached to a motorcycle to support it for movement over snow surfaces. When used as a ski attachment, the attachment comprises two main parts; a single ski which is attached to the front wheel of the motorcycle, which permits the front wheel, while stationary, to slide over the snow; and a driving device for connection to the rear wheel of the motorcycle which may comprise two skis on either side of the device for balance, and an endless traction belt for providing driving contact with the terrain. The driving device utilizes the driving, or rear wheel of the motorcycle to provide the driving force for the attachment. The belt of the present invention provides traction and utilizes the driving force of the motorcycle to drive the ski attachment.
In the ski attachment taught by Harris, propulsion of the motorcycle is provided by contacting the drive wheel of the motorcycle with two sprockets which tangentially contact a driving chain attached to the traction belt. This can be seen in FIG. 5 in the Harris patent. When sprocket 44 contacts the chain 50 directly over roller 48, this configuration, because of the small surface area of contact, and because of the extreme pressures applied on the points of contact, causes the driving chain to wear out quickly. Also, because of the small area of contact between the sprocket and the belt, a certain amount of slippage in the drive system is possible.
The belt construction used by Harris, where a driving chain is attached to the belt is expensive in terms of materials and labor needed to provide such construction. Also, such construction has the disadvantage that separation of the driving chain from the belt can and does occur.
A number of belt driving systems are known in the art, none of which are suitable for application to a motorcycle ski adapter kit.
Chaumont, U.S. Pat. No. 3,887,243 relates to an endless track that is adapted to be used on motor driven vehicles such as tractors, snowmobiles, etc. In the belt described by Chaumont, the sprockets for driving the belt are located on the inside of the track and make driving contact with the top of the belt. Since the traction part of the belt is the bottom of the belt, the driving portion of the belt in Chaumont is separated from the traction portion of the belt.
Freedlander, U.S. Pat. No. 1,828,136 teaches a pulley and a belt having matched teeth used as a driving force. In the pulley and belts taught by Freedlander, the driving force is applied to the inside, or the top of the belt.
Freedlander, U.S. Pat. No. 1,611,829 teaches a driving belt, designed particularly as a fan belt for use in automobiles. The belt taught by Freedlander has a central member composed of rubberized cord fabric cut straight or parallel to the reinforcement cords and in a pre-stretched condition. The tension member of the belt comprises a rubberized fabric cut on the bias, or at an angle, and in a pre-stretched condition. Accordingly, the belt is non-stretchable.
Hallaman, U.S. Pat. No. 3,498,684 teaches a traction belt having lugs on its outer surface and tension cords, made of inextensible but flexible wire cord, embedded in the belt, to provide increased transverse stiffness. Longitudinal tension resisting members 10c are positioned centrally through the thickness of the belt in a closely spaced parallel relationship.
Chaumont, U.S. Pat. No. 3,883,191 teaches an endless track which has a main body made primarily of an elastomeric material which is adapted to be moved in an endless path having a longitudinal axis. The main body comprises an inside surface and a ground engaging surface. The inside surface at 15 is provided with projections 17 which are adapted to be engaged by a cooperating pair of inside drive sprockets.
It is recognized in the art to provide a toothed power transmission belt wherein the teeth have a cross sectional configuration of generally trapezoidal form with a radius between the shorter base of the trapezoid and the angled face, wherein the space between the teeth is at least equal to the major base of the trapezoid and the teeth are for mating with conjugating pulley teeth.
It is also known in the art to provide a toothed power transmission belt wherein the teeth have a cross-sectional configuration composed of two circular intersecting arcs for meshing with mating conjugate curvilinear pulley teeth, for example see U.S. Pat. No. 3,756,091 issued to Miller.
It is also known in the art to provide a toothed power transmission system wherein the dimensional relationship of the belt teeth and the grooves and the pulley teeth and grooves is such that in the longitudinal extent of the belt between the pulleys the height of the belt teeth is greater than the depth of the pulley grooves while as the belt travels around the pulleys, the extremely outwardly facing portions of the belt teeth which confront the pulleys come into contact with the portions of the toothed pulley disposed between the pulley teeth which define the bottoms of the pulley grooves, for example, see U.S. Pat. No. 4,037,485 to Huback. In this case, the meshing of the belt teeth is not of the conjugate form.
The above mentioned art specifically teaches that the toothed power transmission belts are constructed on a precisely defined right circular cylinder wherein the mutually cooperating neutral axis plane is established by said right circular cylinder. The toothed power transmission belts of the prior art are primarily intended to be used for power transmission from one toothed pulley to another toothed pulley.
Accordingly, a need exists in the art for a special flat-type traction belt with a dual purpose toothed surface capable of being driven by toothed sprockets and also provide vehicular propulsion. In particular, a need exists for a special flat-type traction belt with a dual purpose toothed surface capable of being driven by toothed sprockets for use with an adapter kit that is used to convert a motorcycle from a street or highway machine to a multi-terrain, all-weather machine with an emphasis on snow transportation.
Accordingly, it is an object of this invention to provide a special flat type traction belt with a dual purpose toothed surface capable of being driven by two toothed sprockets and also provide traction for vehicular propulsion for multi-terrain.
A further object of this invention is to provide a flat-type traction belt as described above for use with a quick adapter kit that converts a motorcycle from a street or highway machine to a multi-terrain all-weather machine with emphasis on snow transportation.
A further object of this invention is to provide a special flat-type traction belt which is highly abrasion resistant, and has a high tear strength.
A further object of this invention is to provide a flat-type traction belt which is relatively light in weight yet demonstrates great strength and flexibility.
A further object of this invention is to provide a traction belt as described which is inexpensive to build.
Further objects of this invention will become apparent from the following specification and claims.